CN1317078A

CN1317078A - Threaded connection of two metal tubes with groove in threading

Info

Publication number: CN1317078A
Application number: CN99810573A
Authority: CN
Inventors: 西里·诺埃尔; 伊曼纽尔·瓦伦尼
Original assignee: Vallourec Mannesmann Oil and Gas France SA
Current assignee: Wa Lou Rick Of France Oil And Gas Co; Nippon Steel Corp
Priority date: 1998-09-07
Filing date: 1999-09-02
Publication date: 2001-10-10
Anticipated expiration: 2019-09-02
Also published as: EP1110020A1; CA2342715A1; BR9913495A; MY121763A; US6481760B1; AR020883A1; GC0000064A; NO20011171D0; UA66876C2; WO2000014442A1; GC0000063A; NO20011171L; ID29464A; NO334633B1; EA200100322A1; EP1110020B1; ATE216471T1; EA002107B1; JP4275861B2; JP2002524712A

Abstract

A threaded connection for two metal pipes including a male element at the end of a first pipe and a female element at the end of a second pipe, the male element including a male external thread, the female element including a female internal thread. The male and female threads are screwed one into the other. At least one of the male or female threads includes a groove formed in the thread and opening either into a stabbing flank or into a crest of the thread or straddling the stabbing flank and the thread crest. The groove is disposed in the thread so as to increase the flexibility of the portion of the thread which comes into pressure contact with the mating thread or to reduce the contact surfaces or to affect the two aspects at the same time.

Description

What comprise groove in the spiral shell tooth is used for being threaded of two metal tubes

The present invention relates to be used for being threaded of two metal tubes.

This connection is by known, especially in the tandem that is used for cast tube or machining pipe or be used for the oil pipe tandem of oil gas well.

This specification with the bottom in, term " is used for being threaded of two metal tubes " and will be included in that two integral body between the long tube connect and at first long tube and second short tube, as the connection between the pipe joint the two.

API (API) definition:

In standard API 5CT, stipulated that the metal tube that is used for production of oil gas well and structure is connected with screw thread metal pipe;

And in standard API 5B, stipulated to be used for the thread forms of band tapering of the standard of this connection, and the standard spiral shell odontoid that is used for triangle, " circle " and trapezoidal thread.

The triangle of API 5B at each on the male and female element or circular spiral shell odontoid comprise two horizontal flank-carrying flanks with penetrate flank-each and be 30 ° perpendicular to every side on the plane of coupling shaft.

When connecting amalgamation (makeup) end, because the tapering of spiral shell odontoid, each of two flanks contacts with the flank that matches under the metal-metal contact pressure, and between the tooth top of the spiral shell tooth that cooperates and tooth root, there is the gap, under the situation of circular spiral shell tooth, the tooth top of spiral shell tooth and tooth root quilt be rounding considerably.

On each hero and female element, the trapezoidal spiral shell odontoid of API 5B comprises two flanks-carrying flank (load flank) and penetrates flank (stabbing flank)-relative plane perpendicular to coupling shaft and tilt a little, tooth root and tooth top are general parallel with thread taper, the matching fully of the shape of female spiral shell tooth and male spiral shell tooth.

When the amalgamation of this type connection of the trapezoidal thread with API 5B finished, because the tapering of spiral shell odontoid, the tooth top of the one at least of male or female element contacted with the tooth root of the element that matches under the metal-metal contact pressure; In addition, the carrying flank also contacts, and has the gap between flank penetrating, and at least in recurrent situation, the element of connection for example is under the pulling force by the weight of tandem or by the reaction of the carrying of supporting surface.

This connection with axial clearance is called as " the spiral shell tooth with interference ", because they produce radial interference between the thread surface that matches, it causes the metal-metal contact pressure between these surfaces, and cause the increase of amalgamation moment of torsion, this increase to be because the friction (increase) that will overcome.The intensity of radial interference is weighed by the value of radial interference.

As is known, term " radial interference " means when element does not connect, in the diameter difference between the chalaza of matching a bit and on female element on the male element; Radial interference have contact pressure on the occasion of meaning in the contact area that connects; The null value of radial interference means the simple contact that does not have pressure, and the negative value of radial interference means radial clearance.

In other patterns that connect, as at European patent application EP-A-0, to describe in 454,147, the spiral shell odontoid is designed to two horizontal flanks and just in time contacts in the latter stage that is connected to form; On the contrary, between tooth root and the tooth top that matches, the gap can be set.

This connection is called " trapezoidal thread that does not have axial clearance " at the remainder of this specification, can work in axial compression and axial tension or bending.

Other connections, as at U.S. Pat-A-2,211,179, US-A-4,161,332 or US-A-4,537,428 use the double step shape straight thread with trapezoidal spiral shell tooth.This spiral shell odontoid does not generally have radial interference, and the contact between the spiral shell tooth only occurs in the carrying flank, especially the carrying flank place when axial tension is born in connection.

US-RE30647 has described another kind and has been threaded, have the double step shape screw thread and the trapezoidal spiral shell odontoid that are known as wedge shape spiral shell tooth, the width of male and female spiral shell tooth is along the length edge of each step of screw thread, change with the phase coordinated mode, so that be screwed into female element gradually with male screw thread, the axial space between the male and female flank on the element of engagement is reduced to zero; Thereby the transverse teeth side is as supporting surface and locate independently sealing surface.

At the remainder of this specification, the screw thread that term " wedge thread " or " variable-width screw thread " will be used to have feature like this.

US RE34467 has described the improvement of degree of the broadening screw thread on connecting, comprise taper interference screw thread, purpose is to avoid pushed by transition at the tooth root and the lubricating grease between the tooth top of screw thread, and this transition extruding can produce measures the amalgamation moment of torsion mistake in the connection of the type relevant with US RE30647.

International Patent Application WO 94/29627 has been described the improvement of the variable-width spiral shell tooth on connecting, and comprises taper interference spiral shell tooth, and purpose is for forming the connection of high amalgamation moment of torsion.In WO94/29627, with after female flank contacts, the amalgamation of wedge thread is continued in male transverse teeth side, and the whole surface of flank can be applied in high amalgamation moment of torsion, and does not have the danger of plastic deformation.

In great majority are threaded, especially have those of tapered thread, during amalgamation, the amalgamation moment of torsion progressively increases, and/or at a given time, increases suddenly, but under any circumstance, it must remain on below the value of corresponding metal plastic deformation, because plastic deformation causes the permanent deformation of metal, and has the danger of wearing and tearing in the plastic deformation zone after a plurality of amalgamation disengagement effects.

If the slope of a curve of the number of turns that the amalgamation moment of torsion is screwed into relatively is very big, maximum permissible torque will reach after another few relatively number of turns relatively at an element; For example, this is in being threaded of the screw thread with very large interference or has horizontal flank in the connection of trapezoidal thread and do not have axial clearance or have situation in the contacted variable-width spiral shell tooth.

Because machining tolerance causes the variable slope in torque curve, this depends on the processing of hero/female screw thread, can not predict the corresponding maximum torque value that allows under this condition, the final relative position of the element of connection.

When each male and female element also comprise the surperficial and supporting surface of metal to metal seal as, for example in the EP-A-0454147, because the above-mentioned shortcoming of action of screw thread is exaggerated, must be under used hero-female element mated condition at the sealing surfaces of thread head and supporting surface, synchronous in the latter stage that connects amalgamation.

The present invention seeks to provide a kind of connection between two metal tubes, and it utilizes the screw thread with different spiral shell odontoids and joint gap taper, straight or straight-taper, and it can overcome above-mentioned shortcoming.

Be used in the integral body of helical thread portion of term " screw thread " finger element of this specification remainder.Thereby screw thread can be by an independent threaded section or by a plurality of threaded sections, for example, double step shape straight thread part, or partly constitute by the cylindrical tapered thread of the pattern of describing in a tapered thread part and the US-A-5437429, the screw thread that this patent is described is directly-taper.

According to the present invention, be used for that being threaded of two metal tubes is included in the male element of first tube end and at the female element of second tube end, male element comprises a male outside thread, and female element comprises a female internal thread, wherein each thread side is parallel with corresponding flank on male screw thread, male and female screw thread is twisted each other and is closed, this is threaded to one of male at least or female screw thread and comprises the groove that is formed in the screw thread, and it is opened and is penetrating flank, or the tooth top of screw thread, or across penetrating on flank and the screw thread tooth top.

The flank of each the female screw thread fact parallel with corresponding male flank make element can connect into not can be only the flank that matches a bit on bearing capacity.

Term " groove " ' refer to have the cavity of two cell walls and a groove bottom, the length of the expansion in screw thread relatively its wide and dark be grow to, latter's size records in passing the cross section of tubular axis.

The shape of groove is corresponding with the tangent plane of cross section, and the width of groove records on the given depth of this shape.

So far, it is whole solid that the spiral shell tooth is considered to, and past attempts attempts strengthening it.Thereby surprising is, and we have recognized and have thought that it is a kind of significance of structure, and the rigidity of this structure can change by forming a groove within it.

The function that is formed on the groove in the screw thread of the present invention is the contact force that reduces between male and female spiral shell tooth, thereby has especially reduced and the proportional amalgamation moment of torsion of contact force.

For this purpose, groove can be arranged in the screw thread, so that be increased in the flexibility of the helical thread portion that contacts under the pressure of the screw thread that matches, or reduces area of contact, or influences this two aspects simultaneously.

Will be described below the example of the layout of the groove that satisfies these functions on of the present invention being threaded that is used for dissimilar screw threads and is used for difformity spiral shell tooth.

US-A-3882917 and F.P. FR-A-2408061 have described and have been threaded, and wherein one of screw thread has a kind of groove of opening in tooth top, but this groove is connected to obtain self-locking with the structure of thread side is closely continuous, that is, and and anti-the disengagement.

In the situation of US-A-3882917, one of thread side has the rib that stretches out with three faces, and one face abuts against the corresponding flank of matching thread, and other two faces have determined to make the pattern of the groove of rib bending.

In FR-A-2408061, can be used in the trapezoidal spiral shell tooth, the gradient of the flank of trough of belt spiral shell tooth is different from the not gradient of trough of belt spiral shell tooth, and be during amalgamation, under bending force, groove reduces at the width of its opening, and this is because the orientation difference of the flank between the spiral shell tooth that matches causes.

Neither one discloses the function according to the groove in connection of the present invention in those documents, and neither one is applied to female spiral shell tooth, and this flank of locating each spiral shell tooth is parallel with the corresponding flank of male spiral shell tooth.

Thereby groove of the present invention can be formed in the spiral shell tooth of taper, straight or straight-taper, and it has the screw thread of independent or a plurality of steps, interference or does not have the screw thread of axial clearance and have fixing Width of thread or have variable-width along thread variations.

Groove can be formed in triangle, circle or the trapezoidal spiral shell tooth; The term " trapezoidal spiral shell tooth " that is used in the remainder of this specification comprises the screw thread that just carries flank and have swallow-tail form spiral shell tooth that has of the pattern described in the screw thread with negative carrying flank angle of the pattern of describing in the EP-A-0454147 or the USRE30647, or as described half dovetail-shaped threads of WO94/29627.

Groove can be formed on male or female screw thread part or all go up or formation simultaneously on the two.

It also can alternately form on male and female screw thread.

It also can form on male and female screw thread continuously or discontinuously.

For the screw thread that comprises the run-out of thread, groove can only be formed in the screw thread that is become intact screw thread, that is, the screw thread of complete length, or it also can be formed in the not intact screw thread.

Can be with the shape of polytype groove, for example, the combination of semi-circular groove, the U-shaped with parallel or uneven branch, symmetry or asymmetric shape or these shapes especially has the U or the V-arrangement of bottom of the rounding of given diameter or more complicated and asymmetric shape.

The shape of groove is preferably constant on its all length.

When groove was opened tooth top at screw thread, the axis of groove shape can be vertical with coupling shaft or tilts with its vertical line, depends on concrete condition.

Open when penetrating flank when groove, the axis of groove profile can be parallel with coupling shaft, or with its inclination, depend on situation.

Alternatively, the degree of depth of groove and width, or the two, can on its whole length, change.

The bottom of groove preferably has 0.2mm or bigger radius is concentrated in this position to suppress stress.

Preferably, when groove was opened in the tooth top at screw thread, the width that groove records at its opening was less than or equal to 2/3 of spiral shell facewidth degree.

At this specification remaining part, term " spiral shell facewidth degree " refers to highly locate the width that axially records in half of spiral shell tooth, and term " spiral shell tooth depth " refers in the tooth root of the plane internal threads vertical with coupling shaft and the distance between the addendum line.

Preferably, when groove is opened when penetrating flank, groove is less than or equal to 2/3 of spiral shell tooth depth at the width of its opening.

Equally preferably, when groove be positioned at the spiral shell tooth penetrate flank the time, its degree of depth is less than or equal to 2/3 of spiral shell tooth depth.

Equally preferably, when groove was positioned at spiral shell tooth tooth top, its degree of depth was less than or equal to the spiral shell tooth depth, so the bottom of groove is no more than the line of spiral shell tooth tooth root.

Equally preferably, when groove across tooth top with when penetrating flank, its A/F and its degree of depth satisfy simultaneously to be opened in tooth top and groove is opened and penetrated the standard of flank for groove.Reason thus, its degree of depth be less than or equal to spiral shell tooth depth and spiral shell facewidth degree 2/3 in smaller value, and its A/F be less than or equal to spiral shell facewidth degree and spiral shell tooth depth smaller value 2/3.

Preferably, hero that is threaded of the present invention and female element comprise at least one metal to metal seal surface separately, be positioned on the male element each sealing surfaces radially with the female surperficial interference that is positioned at corresponding manner on the female element, so that between male and female element, when amalgamation finishes, produce at least one metal to metal seal contact.

Equally preferably, hero that is threaded of the present invention and female element comprise supporting surface separately, are positioned at supporting surface on the male element and abut against the supporting surface that is positioned on the female element and place under the contact pressure with the position accurately determining to connect amalgamation and finish and with the carrying flank of male and female screw thread.

To the embodiment of different indefiniteness of the present invention be described.

Fig. 1 is screw thread and the pipe joint (T﹠amp that is used to the prior art of two pipes of tapered thread; C) connect.

Fig. 2 is the variation with the connection that is connected same types of prior art.

Fig. 3 is the whole figure that connects of prior art that utilizes double step shape straight thread.

Fig. 4 is the detail drawing that has the screw thread of the round spiral shell tooth that is formed with groove according to of the present invention.

Fig. 5 to 7 is the detail drawings that have the screw thread of the trapezoidal interference spiral shell tooth that is formed with groove according to of the present invention, and each figure has represented the diverse location of groove.

Fig. 8 to 10 also is the detail drawing of the screw thread of the formation that the has groove according to the present invention trapezoidal spiral shell tooth that do not have axial clearance, and each figure has represented the diverse location of groove.

Each comprises three subgraphs among Fig. 4 to 10, the corresponding female screw thread of suffix A, and suffix B is male screw thread, and suffix C links together for the two.

Figure 11 illustrates in greater detail the position of the groove in the spiral shell tooth of pattern shown in Figure 8, and Figure 11 A refers to that female screw thread and Figure 11 B refer to male screw thread.

Figure 12 is that suffix A, B, C, D refer to connection during female screw thread, male screw thread, the amalgamation and the connection of finishing respectively according to the detail drawing of the screw thread of the wedge shape spiral shell tooth with variable-width and groove of the present invention.

Figure 13 is that the amalgamation torque T is with respect to the curve of the number of turns for the pipe connection of using according to the screw thread of Figure 12.

Figure 14 is that suffix A, B, C and D refer to the connection that is connected and finishes during female screw thread, male screw thread, the amalgamation respectively according to the detail drawing of the screw thread of the wedge shape spiral shell tooth with variable-width and groove of the present invention.

All figures are that simple schematic representation, particularly tapering are not drawn in proportion with the gap but be exaggerated can understand the work that is connected better.

The pipe joint 102 that utilizes that Fig. 1 shows according to API 5CT standard is threaded 100 between two metal tubes 101 and 101 '.

The end of each pipe 101,101 ' comprises a male element, and it comprises the male tapered thread 103,103 ' that has circular spiral shell tooth.

Pipe joint 102 comprises two female elements, and the midplane of its relative pipe joint is symmetrical arranged, and each female element comprises the female tapered thread 104,104 ' with spiral shell tooth that the spiral shell tooth with male element is complementary.

Male screw thread 103,103 ' is screwed within the female screw thread that matches 104,104 '.

For the connection of this pattern, standard API 5B has defined thread forms, their size, thread taper, pitch etc.

Although not shown, also can use trapezoidal partially the connection according to standard API 5CT with 5B, similar with Fig. 1 has trapezoidal spiral shell tooth.

Fig. 2 shows a kind of known T﹠amp that has tapered thread 203,203 and have trapezoidal spiral shell odontoid; C connects 200.Pipe joint 202 has bead in the middle, and this bead makes fluid flow to become in pipe 201,201 ' also can not comprised female supporting surface 210 by disturbance, and it abuts against the male supporting surface 209 that the annular end face by pipe constitutes.

Male sealing surfaces 207 of taper and female sealing surfaces 208 are positioned at unthreaded portion and radial interference, so that form elastic contact pressure and the connection of Fig. 2 is sealed between them.

Thereby the taper of male and female supporting surface 209,210 has also strengthened the contact pressure at sealing surfaces 207,208 places and has strengthened the sealing that is connected.

The integral body that Fig. 3 shows between two

pipes

301 and 302 is threaded, and it comprises the straight thread of double step shape.

Pipe 301 end comprises a male element, and it comprises that the male taper shoulder surface 307 of male screw thread 303,303 ', half swallow-tail form of straight double step shape is formed on two male screw thread steps and between the supporting surface 309,309 ' of the every end of male element.

Pipe 302 end comprises female element, and it cooperates with male element and the female taper shoulder surface 308 that comprises female double step shape screw thread 304,304 ', half swallow-tail form is formed on two female screw thread steps and between the supporting surface 310,310 ' of every end of female element.

Connect 300 hero and female screw thread have trapezoidal spiral shell odontoid and twist close after general radial interference not.

Close under the state of finishing twisting, shoulder 307,308 forms the main support faces, and supporting surface 309,309 ', 310,310 ' is only as the safety supports face when the main support face embeds.

Near the end of male element, the conical surface 311 ', 312 ' has formed a pair of interior metal-metallic seal surface respectively on male and female element.Near the end of female element, the conical surface 311,312 has formed pair of outer metal to metal seal surface.Outside a pair of 311,312 of sealing surfaces also can be between shoulder 307,308 and major diameter screw thread step 303,304.

Fig. 4 to 10 and 12,14 schematically shows the effect of the groove of the present invention on being threaded of the pattern shown in Fig. 1 to 3.For clarity sake, Fig. 4 to 10 and 12,14 show several heros and female spiral shell tooth.

Fig. 4 shows the part according to the tapered thread that has circular spiral shell odontoid in the connection of pattern shown in Figure 1 of the present invention, and the spiral shell tooth is formed with groove.

Male spiral shell tooth 11 (Fig. 4 B) comprise carrying flank 13 and penetrate flank 15, and each face becomes 30 ° with each side perpendicular to the plane of coupling shaft, and spiral shell tooth tooth root 17 is roundings.

Groove 21 is radially cut the tooth top of male screw thread, and this groove has the V-arrangement shape of rounding bottom.

Groove 21 at the width of its opening be spiral shell tooth 11 width 25%, its degree of depth equals 50% of spiral shell tooth depth.

Radius in the bottom of groove is 0.4mm.

Female spiral shell tooth 12 (Fig. 4 A) comprises carrying flank 14 and penetrates flank 16, and it matches with male spiral shell tooth, and tooth root is rounded.

Each carrying flank 14 with penetrate flank 16 and become 30 ° with each side perpendicular to the plane of coupling shaft, thereby and be parallel to

male flank

13,15 respectively.

Shown in broken lines and with groove 21 be the groove 22 of identical shaped and position, the tooth top of radially cutting female screw thread substitutes or compensates the groove 21 of male screw thread.

Thereby increased the flexible of spiral shell tooth and reduced the contact pressure of its transverse teeth side at the groove 21 and/or 22 of screw thread tooth top, and solid relatively spiral shell tooth has reduced the amalgamation moment of torsion.

Fig. 5 shows according to of the present invention, the part of the tapered thread of the trapezoidal spiral shell odontoid that has interference in the connection of pattern shown in Figure 2, and the spiral shell tooth has out the groove in penetrating flank.

Male spiral shell tooth 31 (Fig. 5 B) comprise carrying flank 33, and its direction is basic vertical with coupling shaft, and penetrates flank 35, and it becomes 10 to spend tooth root 37 and tooth top 39 with plane inclination perpendicular to this.

Tooth root 37 is parallel with the tapering of screw thread with tooth top 39.

Groove 41 is divided into two-part with male spiral shell tooth 31 parts; Groove has the V-arrangement of rounding bottom, is oriented basic parallel with coupling shaft.

Groove 41 is that 1/3 and its degree of depth of tooth depth is 50% of the facewidth at its width that is penetrating the opening in the flank.

The drift angle of the V-arrangement of groove 41 about 30 ° and V-arrangement are basic parallel with coupling shaft in the branch 42 of male thread root side.

The bottom of groove is the arc of radius 0.4mm.

The shape of female spiral shell tooth 32 (Fig. 5 A) is complementary with corresponding male spiral shell tooth, that is, its profile line is parallel with the profile line of corresponding male spiral shell tooth, and it is parallel to each other especially to carry

flank

33,34, and it is also like this to penetrate

flank

35,36; But the degree of depth of female spiral shell tooth is slightly smaller than the degree of depth of male spiral shell tooth, and tooth root 40 width of female spiral shell tooth are slightly larger than the width of the male tooth top 39 that matches.

Female spiral shell tooth 32 does not comprise groove.

Fig. 5 C schematically illustrates the work that connects when amalgamation finishes.

When connecting amalgamation and finish, the carrying flank 33 that is complementary contacts under pressure with 34, be because, the reaction force of supporting surface or the axial tension that connects for example.Because male carrying flank is parallel with female carrying flank, this contact pressure is distributed on the whole width of carrying flank.

Similarly, contact to tooth root 40 radial interference of the tooth top 39 of male screw thread and female screw thread.On the contrary because above-mentioned geometrical shape, match penetrate between

flank

35 and 36 and male thread root 37 and female screw thread tooth top 38 between provide the gap.

The top 43 of bearing the male spiral shell tooth 31 of

surface

39 and 40 radial interference can elastic bending, and reduces contact pressure, thereby and reduces the amalgamation moment of torsion.

The flexibility on the top 43 of male spiral shell tooth 31 can be adjusted penetrating the position on the flank 35 and the degree of depth of regulating tank by adjusting groove 41.

Owing to do not have radial interference between male thread root 37 and female screw thread tooth top 38, opening existence at the groove that penetrates flank 36 of female screw thread, to be proved to be in work be unsuitable.

In this position of the groove on the tooth of interfering especially to reducing useful near tooth top and the contact pressure between the tooth root on the horizontal plane of the screw thread on metal to metal seal surface; Cause leakage between the sealing surfaces in this high contact pressure; Thereby only provide groove at helical thread portion near load-bearing surface.

Though be not illustrated, also might imagine one and have the connection of the radial interference between the tooth top 38 of the tooth root 37 of male screw thread and female screw thread, and in female screw thread, form groove, and open and penetrating on the flank 36 with symmetrical manner.

Fig. 6 shows the part according to the tapered thread of the trapezoidal spiral shell tooth with interference of the present invention, similar to Fig. 5, but the groove 51 with V-arrangement of rounding bottom is formed in the male screw thread, opens in screw thread tooth top 39.

The effect of groove 51 is at first for reducing the radial interference of

surface area

39 and 40, so that reduce and the proportional frictional force of surface area, next is to be increased in carrying flank 33 and when 34 contact under pressure, the flexibility of the bearing part 53 of screw thread, it also reduces friction, thus and the amalgamation moment of torsion that reduces to connect.

The shape of groove 51 and groove 41 similar, but its radial location and opening in tooth top 39 are towards penetrating flank 35.Thereby, its A/F, for example be male spiral shell tooth width 60%, and its degree of depth is 50% of a spiral shell tooth depth.

As shown in Figure 5, exist groove to prove unsuitable, because male thread root 37 does not produce friction at this at female screw thread tooth top 38.

Fig. 7 shows the part of the tapered thread of the trapezoidal spiral shell odontoid with interference, and itself and Fig. 5's is similar, except the groove 56 of bottom with V-arrangement and rounding is arranged on the male screw thread, penetrates on the flank 35 so that stride on the spot to open at male screw thread tooth top 39 and hero.

Because its position across the two, the direction of the groove 56 in the integral body of spiral shell tooth tilts, and for example the axis of groove shape and screw thread tooth top 39 form 45s.

The layout of groove 56 both can increase the flexibility of spiral shell tooth, and contact pressure is born on its

surface

33,39, also can reduce

contact surface

39,40.

Fig. 8 shows the part that has the tapered thread of the trapezoidal spiral shell tooth that does not form axial clearance according to of the present invention, and groove 61 is formed in the tooth top 39 of male spiral shell tooth 31, and another groove 62 is formed in the tooth top of female spiral shell tooth 32.

The spiral shell tooth of the screw thread in the shape of

spiral shell tooth

31,32 and Fig. 5 is similar; The profile line of especially female spiral shell tooth 32 is parallel with the profile line of corresponding male spiral shell tooth 31, except the tooth top 39 of male spiral shell tooth 31 and the tooth root 40 of female spiral shell tooth 32, the tooth root 40 of male spiral shell tooth is provided so that when amalgamation with the tooth top 38 of female spiral shell tooth does not radially interfere, and

horizontal flank

33,34,35 and 36 is provided in and connects when amalgamation finishes that it just contacts, shown in Fig. 8 C.

Identical with the figure of front, male and

female groove

61,62 has the V-arrangement of rounding bottom.

Identical with the figure of front, the drift angle of the V-arrangement of

groove

61,62 is about 30 °, and the radius on the summit of V-arrangement is 0.4mm.

For example, the degree of depth of

groove

61,62 is 70% of a spiral shell tooth depth, and its A/F at tooth top is 35% of a spiral shell facewidth degree.

Groove

61,62 act as make

half tooth

63,65 the incision male screw thread in and 64 and 65 the incision female screw thread in.

When connecting

flank

33,34,35 and 36 that amalgamation finishes to match and contact, these half teeth are more than solid tooth softness.Have benefited from this increased flexibility, the action of 209,210 in supporting surface such as Fig. 2 is approaching with the transverse teeth side of matching, can be synchronous; In this case, because the cooperation of male and female element is bad, these flanks approaching too early causes the slight elasticity distortion of spiral shell tooth when connecting amalgamation and finish, but can obtain for the accurate location that obtains the required supporting surface 209,210 of sealing surfaces 207,208.Should be too early near occurring in the fraction manufacturing installation.

Following example shows the application of this structure:

Outer tube diameter: 177.8mm (7 ");

The thickness of pipe: 10.36mm (29lb/ft);

Material processed becomes the minimum yield stress of 551Mpa;

Have 6.25% tapering, the tapered thread of 5 trapezoidal spiral shell teeth of per inch (that is, the angle between pitch tapering 45,46 and coupling shaft direction 47 is 1.79 °).

Figure 11 B and 11A show the part of Fig. 8 of the respective shapes with male and female

spiral shell tooth

31 and 32, and this spiral shell teeth size is decided to be axial no any gap after amalgamation.

In the drawings, carrying

flank

33,34 be-3 ° a slight negative angle, and the normal slope that penetrates all relative coupling shaft of

flank

35,36 becomes 13 °.The

tooth top

38,39 of spiral shell tooth is parallel with the bus of pitch tapering 45,46 with

tooth root

37,40, and this bus and coupling shaft are inclined to 1.79 °.

Spiral shell facewidth degree is 1.6mm near 2.54mm and its degree of depth.

Respectively the axle of the

groove

61,62 on male spiral shell tooth 31 and female spiral shell tooth 32 vertical with coupling shaft and they open in

tooth top

39,38.

Groove

61,62 has the

cell wall

71,71 ', 72,72 ' of two inclinations, and is linked to each other by groove bottom 73,74, so as groove be shaped as asymmetric V-arrangement with rounding bottom.

Distance between the axle of

groove

61,62 and the corresponding carrying

flank

33,34 is 1.4mm.

The drift angle of V-arrangement is 35 °, and

wall

71,72 points to carrying

flank

33,34, more tilts with respect to the V-arrangement axle a little than other walls 71 ', 72 '.

Radius in groove 73,74 bottoms is 0.4mm.

The degree of depth of

groove

61,62 is 1mm in Figure 11, promptly 62.5% of the spiral shell tooth depth.Thereby A/F is 38% of a spiral shell facewidth degree.

Though not shown, have being threaded of trapezoidal spiral shell tooth of the present invention and also can be manufactured into when amalgamation, tapered thread does not have axial clearance to have radial interference, and at least one spiral shell tooth has out the groove in tooth top.

Fig. 9 of the present invention shows the part of the tapered thread that has taper spiral shell tooth and axial clearance, as the situation of Fig. 8 but groove 67 in male spiral shell tooth 31, process, open at it and penetrate on the flank 35, to reduce the contact friction surface.

Groove 67 has near basic axle coupling shaft.

As an example, its degree of depth that axially records can be 50% of spiral shell facewidth degree, and at its width of opening be male spiral shell tooth the degree of depth 50%.

The same with the figure of front, its shape is 30 ° V-arrangement roughly, and its end points termination is the circular arc of 0.4mm radius.

Except groove 67, penetrate female that to have groove in the flank be unsuitable.

Figure 10 shows groove 68, and its opening becomes across the male spiral shell tooth tooth top 39 and the hero of connection of the present invention to penetrate on the flank 35, has the tapered thread of trapezoidal spiral shell odontoid, does not have axial clearance as shown in Figure 8.

As the situation among Fig. 7, the relative tooth item of groove and penetrate flank and tilt, and can reduce contact pressure on the flank that laterally matches and rubbing contact surface the two.

Though not shown, might process being connected of spiral shell tooth and the trapezoidal spiral shell odontoid that has groove always according to the present invention, for example groove is positioned at tooth top or across tooth top with penetrate on the flank, and is used to reduce the contact pressure on the carrying flank.

According to the present invention, also might be envisaged in the groove at the tooth top place on the trapezoidal wedge shape spiral shell tooth of straight, taper or straight-taper, this place width male and female spiral shell tooth changes along reach, so that contact pressure is set up in the transverse teeth side of spiral shell tooth when amalgamation finishes.

Figure 12 has illustrated the groove at the tooth top place that is arranged on variable-width wedge shape spiral shell tooth, and this spiral shell tooth is on screw thread that the double step shape straight thread of type shown in Fig. 3 connects 303 ', 304 '.

The male spiral shell tooth 331 of Figure 12 B is for trapezoidal and comprise carrying flank 333, penetrate flank 335, tooth top 339 and tooth root 337, tooth top and tooth root be positioned at the coaxial barrel surface of coupling shaft on.

With respect to the normal of coupling shaft, to carry and penetrate flank and form one jiao, negative value is generally got at this angle, so that spiral shell tooth 331 is the shape of dovetail.

The width l1 of male spiral shell tooth, connects on each step and increases to the screw thread that is positioned at opposite side from the screw thread of the free end side that is positioned at male element.

The female element 332 of Figure 12 A is for trapezoidal and become the dovetail shaped that the shape of male spiral shell tooth 331 matches, and they comprise the carrying flank 334, penetrate flank 336, tooth top 338 and tooth root 340, tooth top and tooth root be positioned at the coaxial barrel surface of coupling shaft on.

Each female spiral shell tooth flank 334,336 is parallel with the flank 333,335 of corresponding male spiral shell tooth respectively.

The width l2 of the female spiral shell tooth on identical step increases to the screw thread that is positioned at opposite side continuously from the free-ended screw thread that is positioned at female element, with the coordinated mode mutually that increases progressively at the width of the male spiral shell tooth of male screw thread.

Female spiral shell tooth comprises groove 362, and it is opened in tooth top 338, and its shape is similar to the groove among Fig. 8 A with the position.

Figure 12 C shows the hero and the female screw thread of a step in the amalgamation process, has a constant space x between the carrying flank 333,334 of the screw thread of each thread engagement that matches with it.

In addition, such straight thread does not have radial interference between the tooth top that matches and tooth root 337-338,339-340.

Be screwed in the female element with male element, the space between the horizontal flank that matches is reduced to zero, shown in Figure 12 D.

If turn continuously to surpass this point, male transverse teeth side 333,335 is pressed in the female flank 334,336 that matches, and is cooperating contact pressure between the flank with being screwed into continuously and increase.This causes increasing very apace on the amalgamation moment of torsion, and depends on the surface area of the increase of flank, and amalgamation can be finished under high moment of torsion.

Similar to the figure of front, groove 362 has the V-arrangement of rounding bottom, and the drift angle of the V-arrangement of groove is about 30 °, and the radius on V-arrangement summit is 0.4mm.For example, its degree of depth is 70% of a spiral shell tooth depth, and its width at opening is 35% of a spiral shell facewidth degree.

Groove 362 is with in half tooth 364 and the female spiral shell tooth 332 of 366 incisions, and this half tooth is more than solid tooth softness.

In having this spiral shell tooth 331,332 of variable-width, exist groove to cause amalgamation torque T-element to rotate the gradient of N curve, shown in the relative curve D of curve E among Figure 13, curve D relates to a kind of similar spiral shell tooth that does not have groove, though because the existence of groove, the maximum amalgamation moment of torsion that allows only reduces a little.

In having this spiral shell tooth of variable-width, exist groove also can cause torque T to surpass the qualification effect certainly of a specific threshold.This had prolonged the possibility of rotating N before reaching maximum permission amalgamation moment of torsion, and made one or more pairs of separate sealing surfaces 307,308 utilize one or more pairs of supporting surfaces 309,309 ', 310,310 ' can correctly locate under all heros-female mated condition.

Figure 14 shows the groove of the tooth top that is positioned at wedge shape spiral shell tooth, and this spiral shell tooth is variable-width on the screw thread 203,204 of the tapered thread connection of pattern shown in Figure 2.

Male spiral shell tooth among Figure 14 B be trapezoidal shape and comprise the carrying flank 233, penetrate flank 235, tooth top 239 and tooth root 237, the tooth top of spiral shell tooth is positioned at coaxial with coupling shaft with tooth root and has on the conical surface of identical tapering.

In a kind of variation (not shown), the tooth top of spiral shell tooth and/or tooth root can be parallel with coupling shaft, pitch surface, although be taper.

The relative normal of coupling shaft, carrying flank 233 forms one jiao, negative value is generally got at this angle, and the method that penetrates flank 235 relative coupling shafts forms one jiao mutually, this angle generally get on the occasion of.

Diverge to for flank 233,235 on the direction that moves towards tooth top 239 at the carrying flank of spiral shell tooth and the angle that penetrates between the flank, therefore, the spiral shell tooth is a kind of shape that is known as half dovetail.

The width of male spiral shell tooth increases continuously to the spiral shell tooth that is positioned at opposite side from the spiral shell tooth of the free end that is positioned at male element.

Male spiral shell tooth comprises groove 261, and it is opened in screw

thread tooth top

239,61 similar among its shape and layout and Fig. 8 B.

The female spiral shell tooth 232 of Figure 14 A is trapezoidal for what match with the shape of male spiral shell tooth 231, and they comprise carrying flank 234, penetrate flank 236, tooth top 238 and tooth root 240.

Each flank 234,236 of female spiral shell tooth is parallel with the flank of corresponding male spiral shell tooth respectively.

The width of female spiral shell tooth increases to the screw thread that is positioned at opposite side continuously from the free-ended screw thread that is positioned at female element, with the coordinated mode mutually that increases progressively at the width of the male spiral shell tooth of male screw thread.

Figure 14 C shows at hero during the amalgamation and female spiral shell tooth: be mated between the carrying flank of each spiral shell tooth that the spiral shell tooth together works and can seeing that a constant space x is arranged.

Be screwed in the female element with male element, the space x between the transverse teeth side of matching is reduced to zero, shown in Figure 14 D.If amalgamation is proceeded to surpass this point, male transverse teeth side 233,235 is pressed into the female flank 234,236 that matches, and the contact pressure between the flank that matches increases with the lasting of amalgamation.

This causes increasing very apace of amalgamation moment of torsion, and depends on the surface of the increase of flank, and amalgamation can be finished under very high moment of torsion.

In addition, wedge shape spiral shell tooth tapered thread to this pattern, can be arranged to when amalgamation is finished, between the tooth top of spiral shell tooth 237-238 that matches and/or 239-240 and tooth root, there is a radial interference, thereby the space between the female screw thread of male screw thread 23 complete filling, and/or the space between the male screw thread of female screw thread complete filling.Figure 14 D shows situation male and that female screw thread fills up fully, thereby, screw thread self locking, and make that to be present in the tooth top and the lubricating grease between the tooth root that match invalid when amalgamation finishes, this situation is the reason of amalgamation moment of torsion mistake measurement.Preferably, it is arranged to produce a radial interference prior to the transverse teeth contacts side surfaces that matches.

As among the figure in front, male groove 261 has the V-arrangement of rounding bottom, and the radius that the drift angle of the V-arrangement of groove is about the summit of 30 ° and V-arrangement is 0.4mm.Its degree of depth for example, is 70% of spiral shell tooth depth, and its width at the opening of tooth top is 35% of a spiral shell facewidth degree.

Groove is in the male spiral shell tooth 231 of half tooth 263,265 incision, and half tooth is more than solid spiral shell tooth softness, and groove 362 identical functions in being connected of execution and Figure 12, and this function is described in above.It also can make extending axially with the radial interference of tooth top and tooth root of flank horizontal when amalgamation finishes soon synchronous better.

Connection of the present invention can not play any restriction in these several embodiments that provide with multiple variation processing.

Especially, the present invention can be applied to:

Being threaded of integral body as shown in Figure 3, the male element of the end of the setting and first long metal pipe and the female element that is arranged on the end of second long metal pipe;

And be applied to as depicted in figs. 1 and 2 T﹠amp; C connects, and wherein two long metal pipes that have male element in its end connect by metallic pipe coupling, and every end of this pipe joint is provided with female element, this T﹠amp; C connects and comprises two of the present invention being threaded.

Claims

1. one kind is used for being threaded of two metal tubes, be included in the male element of first tube end and at the female element of second tube end, male element comprises male outside thread, female element comprises female internal thread, wherein each spiral shell tooth flank is parallel with the flank of corresponding male spiral shell tooth, male and female screw thread is twisted each other and is closed, it is characterized in that, in order to reduce the purpose of the contact force between male and the female screw thread, at least one of hero or female screw thread comprise groove, this groove comprises two cell walls and a groove bottom, and it is arranged in the body of spiral shell tooth and opens in penetrating flank or in the tooth top or across penetrating on flank and the tooth top.

2. as claimed in claim 1 being threaded is characterized in that, groove is continuous on the length direction that advances of spiral shell tooth or screw thread.

3. as claimed in claim 1 or 2 being threaded is characterized in that groove has the bottom of V-arrangement profile and rounding.

4. as each described being threaded in the claim 1 to 3, it is characterized in that the bottom of groove has 0.2mm or bigger radius.

5. being threaded according to any one of claims 1 to 4 is characterized in that the width of opening the opening of the groove (21,22,51,61,62,261,362) at tooth top is less than or equal to 2/3 of spiral shell facewidth degree.

6. being threaded according to any one of claims 1 to 4 is characterized in that the width of opening at the opening that penetrates the groove of flank (41,67) is less than or equal to 2/3 of spiral shell tooth depth.

7. being threaded according to any one of claims 1 to 4 is characterized in that, be less than or equal to across tooth top and the width of opening that penetrates the groove (56,58) of flank the width of spiral shell tooth or the degree of depth smaller value 2/3.

8. being threaded according to any one of claims 1 to 4 is characterized in that the degree of depth that is positioned at the groove (21,22,51,61,261,362) of tooth top is less than or equal to the degree of depth of spiral shell tooth.

9. being threaded according to any one of claims 1 to 4 is characterized in that, is formed on the degree of depth that penetrates the groove (41,67) in the flank and is less than or equal to 2/3 of spiral shell facewidth degree.

10. being threaded according to any one of claims 1 to 4 is characterized in that, is less than or equal to the smaller value in 2/3 and the spiral shell tooth depth of spiral shell facewidth degree across tooth top and the degree of depth that penetrates the groove (56,58) of flank.

11., it is characterized in that male and female screw thread is taper, has trapezoidal spiral shell tooth as each described being threaded in the claim 1 to 10, it is arranged on the step or on a plurality of step.

12. as claimed in claim 11 being threaded is characterized in that, when amalgamation is finished, and at least one tooth item and the tooth root radial interference that matches male and female screw thread.

13. as claimed in claim 11 being threaded is characterized in that, male and female screw thread is trapezoidal, no radial clearance.

14., it is characterized in that male and female screw thread is straight as each described being threaded in the claim 1 to 10, be arranged on one or more steps, or be directly-taper.

15., it is characterized in that the width of male and female spiral shell tooth changes to constitute wedge thread with mutual coordinated mode along whole length screw thread or each threaded section as each described being threaded in the claim 11 to 14.

16., it is characterized in that male and female screw thread is taper as each described being threaded in the claim 1 to 10, have circular spiral shell tooth according to standard API 5B.

17. as each described being threaded in the claim 1 to 16, it is characterized in that, male element comprises at least one male sealing surfaces (207,311,311 '), and female element comprises at least one female sealing surfaces (208,312,312 '), when amalgamation finished, corresponding hero and female sealing surfaces radial interference were so that produce at least one metal to metal seal contact between male and female element.

18. as each described being threaded in the claim 1 to 17, it is characterized in that, male and female element comprises at least one supporting surface separately, and when connecting the amalgamation end, the supporting surface of male element (209,307) is against the supporting surface (210,308) of corresponding female element.

19., it is characterized in that it is integrated (300) as each described being threaded in the claim 1 to 18.

20., it is characterized in that it is screw thread and pipe joint pattern (100,200) as each described being threaded in the claim 1 to 18.